= Programming Neo FreeRunner LEDs =

Neo FreeRunner has three LED indicators:

|| '''Color''' || '''Location'''      || '''IO Port/pin''' ||
|| orange      || behind power button || GPB0              ||
|| blue        || behind power button || GPB1              ||
|| red         || behind aux button   || GPB2              ||

Combination of orange and blue behind the power button should give purple.

== Port B Control Registers ==

|| '''Register''' || '''Address''' || '''Description''' || '''Reset value''' ||
|| GPBCON         || 0x56000010    || Pin configuration || 0x0               ||
|| GPBDAT         || 0x56000014    || Data in/out       || undefined         ||
|| GPBDN          || 0x56000018    || Pull-down disable || 0x0               ||

GPB has 11 pins (GPB0 through GPB1 inclusive).

Register descriptions:
 * GPBCON: Two configuration bits per pin (GPBCON![1:0] for GPB0, GPBCON![3:2] for GPB1, etc.), 00 = Input, 01 = Output, 10 = XXX, 11 = reserved. XXX refers to internal signals, different for each pin.
 * GPBDAT: Obvious, write in output mode and read in input mode.
 * GPBDN![10:0]: 0 = pull-down enabled, 1 = pull-down disabled.

For blinking LEDs, we select output mode (0b01) for GPB0..GPB2. Pull-down should be disabled. Then write to GPBDAT![0:2].

References:
 * [http://www.opatnet.cz/elektronika/datasheet/U/um_s3c2442b_rev12.pdf Samsung S3C2442B Processor Datasheet] Porg B Control Registers, Page 9-10.
 * [http://downloads.openmoko.org/developer/schematics/GTA02/Schematics_Freerunner-GTA02_A5-A7cumulative_public_RC0.pdf Neo FreeRunner Schematics] MCU, sheet 3.

Notes:
 * Not verified